Deflection transducers, such as that shown and described in U.S. Pat. No. 4,042,049 to Reichow, et al., have in the past been used to measure vehicle loads. Such transducers have been manufactured in various forms and configurations, and, in use, are typically positioned on a structural member of the vehicle such as an axle or a structural part of the suspension system. The purpose of using a deflection transducer in such a manner is to obtain a fast and accurate "on-board" indication of vehicle load weight. An onboard weighing system permits convenient measurement of loads at any time, without the necessity of using a conventional scale, at the time of initial loading, or when part of the original load is removed from the vehicle or when a partial new load is added. An onboard system prevents accidental overloads and the possible fines and other inconvenience associated therewith, while insuring that the vehicle is loaded substantially to its permitted capacity whenever possible.
However, conventional onboard weighing systems, including the system shown in the '049 patent, are typically subject to inaccurate or fluctuating results, due to twisting and possibly other movements of the transducer structure caused by normal movement of the vehicle. Such movements are not indicative of vehicle load, but do have an effect on transducer output. Such transducers have also been found to be subject to damage and breakage due to the typically harsh operating environments of such systems, such as, for instance, a logging truck.
Hence, there is a need for a rugged deflection transducer capable of operating in harsh on-board vehicle environments and designed so that it is not responsive to twisting movements, but substantially only to tensile and compression deflection, which provides the desired accurate indication of vehicle load.
The mounting of such transducers is also an important factor relative to the accuracy of the transducer results and its performance in general. Specialized devices are known, such as shown in U.S. Pat. No. 4,102,031 to Reichow, et al., for insuring that the mounting elements for the transducer are spaced apart a selected distance and have a particular configuration in order to properly receive the transducer. However, present devices, including the one shown in the '031 patent, and the described methods for their use, have not provided completely satisfactory results, as imprecise positioning of the mounting elements can still occur, which in turn will result in poor performance of the transducer when the transducer is connected to the mounting elements.
Hence, there is also a need for a transducer mounting structure which will insure precise positioning of the transducer structure.